Technical Field
This disclosure relates to an image forming apparatus in which a sheet or a recording medium of a sheet bundle that is contained in a sheet container is fed therefrom by a surface movement of a sheet feeding body to which the sheet is pressed, and is separated from the other sheets of the sheet bundle in a separation nip region formed by a contact of the sheet feeding body and a sheet separating body.
Related Art
As an example of known image forming apparatus, some image forming apparatuses do not include a pickup roller and causes a sheet feed roller to function as a pickup roller. This configuration can achieve a reduction of cost without a pickup roller.
For example, in this configuration, a comparative sheet tray of a known image forming apparatus accommodates multiple sheets as a sheet bundle therein. A sheet feed roller is disposed in the vicinity of the sheet tray. The leading end of the sheet bundle contained in the sheet tray is biased by a movable bottom plate of the sheet tray to an upward direction, so that the leading end of the sheet bundle contacts the sheet feed roller to form a pressed region. In the vicinity of the pressed region, the sheet feed roller and a sheet separating roller are in contact with each other to form a sheet separation nip region.
As the sheet feed roller rotates, an uppermost sheet placed on top of the sheet bundle is fed from the sheet tray toward the sheet separation nip region. At this time, a subsequent sheet or subsequent sheets immediately below the uppermost sheet may be fed together with the uppermost sheet from the sheet tray. This sheet feeding operation is called as “multifeed”. When multiple sheets are held in the sheet separation nip region due to the misfeed, the uppermost sheet directly contacting the sheet feed roller is fed in a sheet feeding direction along with movement of a surface of the sheet feed roller. By contrast, the other sheets such as the subsequent sheet(s) are conveyed by the sheet separating roller to return to the sheet tray along with movement of a surface thereof in an opposite direction to the sheet feed roller in the sheet separation nip region. According to this conveyance back to the sheet tray, even when multifeed occurs, a single sheet, i.e., the uppermost sheet, which directly contacts the sheet feed roller is separated from the other sheets in the sheet bundle. Thereafter, the uppermost sheet is conveyed toward an image forming part of the image forming apparatus.